When signals are transmitted via telecommunication channels from a transmitter to a receiver, signals, in the form of pulses for example, which convey digital data bits, are fed at the transmitter end to a telecommunication channel. In the case of cable-supported telecommunication networks, the telecommunication channel is realized by a cable connection. While the signals are being propagated in the telecommunication channel changes of the signal form generally occur, for example due to frequency-dependent attenuation characteristics of the telecommunication channel. In order to permit normal processing of the signals at the receiver end, it is essential that the signals conveyed by the telecommunication channel have not only sufficient signal strength, for example pulse height, but also that the signal form corresponds to certain criteria. The criteria, for example of pulse width or flank steepness, which such a signal has to meet, can be specified in the context of a standard, for example ITU G.703, ANSI T1.403, FCC68 or FTZ 221. Therefore a device is required at the transmitter end, which produces signals in such a manner that the signals conveyed by the telecommunication channel have a certain signal form, which corresponds to a standard signal form specified by the standard. It is possible to reduce cross modulation of adjacent telecommunication channels by pre-distorting the signal form of the signal produced according to the characteristics of the telecommunication channel, for example the cable length, and in attenuation of the signal. Sometimes even adaptation of the attenuation is necessary, as a function of the cable length for example. The attenuation takes place, in order to reduce said cross modulation from adjacent telecommunication channels. The pre-distortion takes place so that at a receiver end a wrong cable length is not concluded through evaluation of the received signal on the basis of its attenuation.
Conventionally, the various signal forms and the adaptation or pre-distortion of the signals, in order to take the characteristics of the telecommunication channel into consideration, are realized by means of analog circuits.
Problems with the analog production and adaptation of the signals exist for example in a large surface area, which is required for implementing the circuits on a semiconductor chip, costly portability to other technologies and high time expenditure for testing and trimming the circuits during manufacture.
The object of the present invention is to make a device available for the production of standard-compliant signals, which solves the problems indicated above at low manufacturing cost, whereby the signals with a certain signal form are to be produced particularly by very simple and therefore robust ways and means.